Erythromycin Eletriptan

CYP3A4 enzyme. A clinical study has shown that coadministration of eletriptan with ketoconazole, erythromycin, verapamil, and fluconazole increased the Cmax3> cl... 

ALMOTRIPTAN, ELETRIPTAN MACROLIDES -CLARITHROMYCIN, ERYTHROMYCIN, TELITHROMYCIN t plasma concentrations of almotriptan and eletriptan, with risk of toxic effects, e.g. flushing, sensations of tingling, heat, heaviness, pressure or tightness of any part of body including the throat and chest, dizziness Almotriptan is metabolized mainly by CYP3A4 isoenzymes. Most CYP isoenzymes are inhibited by clarithromycin to varying degrees, and since there is an alternative pathway of metabolism by MAO-A, toxicity responses will vary between individuals Avoid co-administration... 

Erythromycin markedly raises the plasma levels of eletriptan. Clarithromycin, josamycin and troleandomycin are predicted to interact similarly. Almotriptan levels may be raised by erythromycin. Clarithromycin does not significantly alter the pharmacokinetics of sumatriptan. 

A clinical pharmacokinetic study by the manufacturers of eletriptan found that erythromycin 1 g increased the maximum serum levels of eletriptan 2-fold, the AUC 3.6-fold and prolonged its half-life from 4.6 to 7.1 hours. 

The macrolides are, to varying degrees, inhibitors of the cytochrome P450 isoenzyme CYP3A4, by which eletriptan is metabolised. Therefore giving erythromycin raises eletriptan plasma levels. Sumatriptan is not metabolised by CYP3A4 and therefore does not interact. 

Information is limited but an interaction between eletriptan and erythromycin appears to be established. Because of the elevated levels seen, the manufacturers advise against their concurrent use. Other drugs that are potent CYP3A4 inhibitors are predicted to raise serum eletriptan levels similarly. Such drugs include clarithromycin josamycin, and troleandomycin. In addition, the US manufacturers recommend that eletriptan should not be given within 72 hours of clarithromycin or troleandomycin. ... 

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